Design of wearable rectennas for RF energy harvesting -

Abstract

The modern life has tremendously changed. Nowadays, we cannot imagine our lives without our indispensable smart phones and laptops. However, the main problem of these devices is the limited life battery. One other aspect of the modern life is our continuous movement that may take us to places where no electrical power sources are available. This thesis studies the design and fabrication of textile-based rectennas for RF energy harvesting as a possible solution of the problems stated above. First, a method for electrical characterization of textiles by the use of quarter-wavelength stub-lines band-stop filters is presented. The proposed method is used for the characterization of a jeans textile that is, in turn, used for the design of a circularly polarized wearable antenna for the 2.45GHz ISM band. A prototype of the designed antenna is fabricated and tested showing a good analogy with the simulated results. Afterwards, multiple rectifying circuits targeting different bands are designed fabricated and tested showing good results for both conversion efficiency and output DC voltage. The thesis is divided into five chapters. Chapter 1 provides a brief overview of RF energy harvesting by the use of rectennas. Chapter 2 presents a literature review on wearable antennas. Chapter 3 is an introduction on circular polarization and the methods applied to design circularly polarized antennas. Chapter 4 presents the thesis wok and is divided to three parts. Part 1 presents the proposed method for electrical characterization of textiles. Part 2 includes the antenna design, analysis and measurement results. Part 3 presents the rectifying circuits design, analysis and measurement results. Finally, Chapter 5 presents a conclusion of the thesis and possible future extension.